Without limiting the scope of the invention, its background is described in connection with single inline memory modules, as an example.
Heretofore, in this field, integrated circuits have been formed on semiconductor wafers. The wafers are separated into individual chips and the individual chips are then handled and packaged. The packaging process is one of the most critical steps in the integrated circuit fabrication process, both from the point of view of cost and of reliability. Specifically, the packaging cost can easily exceed the cost of the integrated circuit chip and the majority of device failures are packaging related.
The integrated circuit must be packaged in a suitable media that will protect it in subsequent manufacturing steps and from the environment of its intended application. Wire bonding and encapsulation are the two main steps in the packaging process. Wire bonding connects the leads from the chip to the terminals of the package. The terminals allow the integrated circuit package to be connected to other components. Following wire bonding, encapsulation is employed to seal the surfaces from moisture and contamination and to protect the wire bonding and other components from corrosion and mechanical shock.
Conventionally, the packaging of integrated circuits has involved attaching an individual chip to a lead frame, where, following wire bonding and encapsulation, designated parts of the lead frame become the terminals of the package. The packaging of integrated circuits has also involved the placement of chips on a flexible board where, following adhesion of the chip to the surface of the flexible board and wire bonding, an encapsulant is placed over the chip and the adjacent flexible board to seal and protect the chip and other components.
Commonly, integrated circuit packages are attached to other components such as single inline memory modules which are typically referred to as SIMMs. SIMMs may, for example, be used to increase the memory of typically personal computers. As memory demands increase, so has the need for increased Input/Output (I/O) capacity and memory capacity of SIMMs. Efforts to enhance these capacities, however, have been limited by the amount of space available in the environment in which the SIMMs operate.
Therefore, a need has arisen for high density SIMMs and a process for producing high density SIMMs that provide for the stacking of integrated circuit packages on the SIMMs. A need has also arisen for materials and methods that lead to increases in I/O and/or memory capacity. Further, a need has arisen for a flat, double-sided integrated circuit package that provides protection to the wire bonding and silicon chip during subsequent manufacturing and testing steps and from the environment of its intended purpose.